Installation tool for a blind fastener and installation procedure for a fastener

ABSTRACT

An installation tool for a fastener of the “pull screw” type, comprising a breakable gripping element includes a body, a first sleeve movable axially and rotationally in the body that can drive the gripping element, a second sleeve movable axially in the body and immovable in rotation, and a driving device provided with a turning shaft. 
     The shaft comprises a first free wheel for driving the first sleeve in rotation, a second free wheel, and a driving element positioned coaxially around the second free wheel. The driving element cooperates using a helical link with the second sleeve. The first free wheel drives the first sleeve in rotation in a first rotation direction of the shaft. The second free wheel brings the driving element in rotation in a second rotation direction of the shaft to move the second sleeve axially, allowing full setting in a single operating sequence.

This invention concerns an installation tool for a blind fastener in astructure.

A “blind” fastener is commonly referred to as a fastener that can beinstalled in structures to be assembled from a single side, called frontor accessible side, by deforming a part of the fastener placed on therear side, accessible or otherwise, of said structures. Deformationtakes place radially outwardly during a pulling or torqueing phase, toform a bulb or flaring, said deformation in abutment against the rearside. The structures to be assembled are thus held tight between a headof the fastener placed in abutment against the front face, and thedeformed part in abutment against the rear face.

Among the types of blind fasteners, there is a first type called a“pull-thru” rivet, comprising a sleeve and a breakable mandrel linkedtogether at one end of the fastener, with the rivet installed byapplying only to the mandrel a pulling force while maintaining thesleeve stationary in translation, until fracture of the mandrel withapplication of a predetermined pulling force. A second type called a“screw rivet”, comprises a threaded sleeve and a threaded mandrel, withthe rivet installed by applying a torque only to the mandrel whilemaintaining the sleeve stationary in rotation, until fracture of themandrel with application of a predetermined torque. A third typecomprises blind nuts, comprising a threaded nut and a removable mandrel,with the nut installed by screwing the removable mandrel in the nut, bypulling or turning the mandrel until a given pulling or torque setpoint,then by unscrewing the mandrel from the installed nut. Finally, a fourthtype called “pull-torqued”, comprises a pin equipped with a head and agripping element, and a threaded sleeve equipped with a collar, to whicha relative pulling force is applied to move the position of the pin withrespect to the threaded sleeve and deform a portion of the sleeve toform a bulb against the rear face of said structure. In this last type,the gripping element is broken with the application of a predeterminedtorque. Such a fastener is, for example, described in the FR3016417application of the applicant.

One objective of the invention is to provide a manual installation toolfor blind fasteners of the “pull-torqued” type.

For this, the invention provides an installation tool for a fastener ina structure via the front face of the structure.

The fastener comprises a shank with a head and a threaded end, agripping element that can be fractured with the application of apredetermined fracture torque and a threaded sleeve able to be deformedoutwardly to form a bulb against a rear face of said structure.

The installation tool comprises:

-   -   a body, substantially of a revolution, extending along a        longitudinal X axis, comprising at a first front end an axial        opening allowing feedthrough of the gripping element and the        fastener head,    -   a first sleeve movable axially and rotationally in the body,        capable of driving the gripping element of the pin in axial        translation and in rotation around the X axis;    -   a second sleeve movable axially in the body and immovable        rotationally, said second sleeve being arranged to drive the        first sleeve in axial translation;    -   a rotational drive means comprising a rotary shaft provided        with:        -   a first free wheel which can drive the first sleeve in            rotation in a first rotation direction of the shaft,        -   a second free wheel that can rotate a driving element            arranged coaxially around said second free wheel in a second            rotation direction of the shaft, opposite to the first            rotation direction, with the driving element cooperating via            helical link with the second sleeve so as to move said            second sleeve in axial translation.

The installation tool obtained is used to install blind fasteners of the“pull-torqued” type with a simple and mechanically robust architecturethat requires few elements to achieve the pulling movement and rotationmovement performed successively to install a fastener.

The installation tool for a fastener according to the invention alsopresents preferably all or some of the following characteristics, takenalone or in a technically operable combination:

-   -   the driving element is a threaded pin, a ball screw, a roller        screw or a worm screw.    -   the first sleeve comprises movable elements adapted for        cooperating with the blocking portion of the gripping element of        the fastener to secure the fastener in the axial direction with        the first sleeve.    -   a first ring is positioned on the first sleeve to be capable of        sliding between a first position in which the movement of        movable elements is blocked in the radial direction and a second        position in which the movement of movable elements is free in        the radial direction.    -   a second ring is capable of sliding along the axial direction on        the body and interfaced with the first ring to bring the first        ring only to the second position.    -   the first free wheel is slidably mounted in the axial direction        on the turning shaft.    -   the first free wheel is mounted on a third ring slidable in the        axial direction on the turning shaft.    -   a compression spring is placed between the third ring and the        driving element.    -   a spring device is secured to an end of the driving element and        to another end of the body; this spring device is tensioned upon        rotation of the shaft in the second direction and slackens to        push the driving element when the rotation of the turning shaft        is stopped and/or reversed.    -   the spring device is a torsion spring or a spiral spring.

The invention also concerns an installation procedure for a fastenerusing an installation tool according to the invention.

According to the procedure it consists of the following steps:

-   -   engaging the gripping element for a fastener to be installed in        the opening of the body of the installation tool to secure the        fastener in translation and rotation with the first sleeve and        engaging the fastener in an opening in the structure, then;    -   rotating the shaft in the second direction to move the second        sleeve in axial translation, which drives the first sleeve in        axial translation in the pulling direction of the fastener pin,        for a distance ensuring the formation of a bulb via deformation        of the sleeve, then;    -   rotating the shaft in the first rotation direction to drive the        pin in rotation to the tightening torque of the pin for which        the gripping element separates from the rest of the pin via a        fracture at the level of a shear groove.

Other objects, features and advantages of the invention appear onreading the description of the invention creation procedures, adescription relating to drawings in which:

FIG. 1 is a cross-section of a blind fastener of the prior art of the“pull-torqued” type;

FIG. 2 is a cross-section of the installation tool in a restingconfiguration,

FIG. 3 is a cross-section of the installation tool and the fastener fromFIG. 1 in a configuration in which the fastener is inserted in theinstallation tool and through a structure,

FIG. 4 is a cross-section of the installation tool and the fastenerinserted in a structure during a bulb formation step;

FIG. 5 is a cross-section of the installation tool and the fastenerinserted in a structure during a torqueing step;

FIG. 6 is a detailed cross-section of the installation tool and thefastener inserted in a structure during a fracture step of the grippingelement of the fastener;

FIG. 7 is a detailed cross-section of the installation tool and thebroken gripping element of the fastener during an ejection step.

To facilitate understanding of the drawings, only the elements necessaryfor understanding the invention are shown. The same elements have thesame references from one drawing to another.

Attention is drawn to the fact that the cross-sections of the noseequipment presented on the various figures are not shown in the sameaxial plane. In particular, views 2, 3 and 7 are shown in a first axialplane and views 4, 5 and 6 are shown on another axial plane.

With reference to FIG. 1, a blind fastener 10 of the “pull-torqued” typeto which the invention applies comprises a pin 12 and a sleeve 14. Thepin 12 comprises a gripping element 16 capable of being broken duringinstallation of the fastener, a rupture groove 18, a countersunk head20, a cylindrical shank 22 and a threaded end 26. The gripping element16 comprises a first gripping portion 28 in the form of a cylinder, ablocking portion 30 and a second gripping portion 32, comprising splinesdistributed over the external surface.

The sleeve 14 comprises an enlarged collar 40 capable of receiving thecountersunk head 20, and a tubular shank 42 including a tapping 48,placed at the end of the sleeve 14, opposite the collar 40. The threadof the pin 12 and the tapping of the sleeve 14 are complementary. Thetubular shaft 42 comprises a deformable zone, not indicated on thedrawing, with a stiffness less than the stiffness of other portions,capable of forming a bulb when pulling is applied.

FIG. 2 is a cross-section of the nose equipment 200 of a tool adapted toinstallation of a blind fastener 10 previously described. The equipmentnose comprises a body 210, substantially a revolution, substantiallycylindrical, hollow extending along an axis X, including a first end 212and a second end 218 opposite the first. For convenience, in theremainder of the description the first end 212 is called the front endand indicates the “forward” direction, whereas the second end is calledthe rear end and indicates the “rearward” direction. The terms “intranslation” and “axially” are used in an equivalent manner to designatea linear movement along the X axis.

The front end of the body (210) comprises a contact surface 214 arrangedto enter into contact with the collar 40 of the threaded sleeve, and anopening 216 sufficient in diameter to enable passage of the grippingelement 16 and the head 20 of the pin 12 within said body.

The body 210 receives a first sleeve 220, movable in rotation and intranslation within said body. The first sleeve is of a substantiallytubular revolution around the X axis of the body. It extends between thefirst end close to the front end 212 of the body, and a second oppositeend. A first ring 222 is located on a first portion of the first sleeve220 adjacent to the first end of the first sleeve. The elements 224,distributed around the axis, movable in at least one component of theradial direction are maintained within the body 210 between the frontend 212 of the body and the first sleeve 220. The first ring 222 ismovable axially on said first portion of the first sleeve, between afirst position in which the movable elements are partially surrounded bythe first ring 222 (FIG. 2) and free to move radially, and a secondposition in which the movable elements are totally surrounded by thefirst ring 222 (FIG. 3) that blocks their movement in the radialdirection.

A first compression spring 226 is located between the first ring 222 anda second sleeve 230. Under the effect of the first compression spring226, the first ring 222 is pushed axially forward. In the restingposition of FIG. 2, the travel of the first ring 222 forward is limitedby the movable elements 224 whose ends closest to the front form a conepresenting an external diameter greater than the internal diameter ofthe first ring 222.

A second ring 228 is positioned around the body 210, close to the frontend 212 of said body. The second ring 228 can slide along the bodytoward the rear, against a second compression spring 229.

The second sleeve 230 is housed within the body 210. It is movableaxially within the body but maintained immovable in rotation. The secondsleeve in revolution is substantially tubular around the X axis of thebody and extends between, at the front, an end of a first portion 232close to the second end of the first sleeve 220, and at the rear, asecond opposite end. The second sleeve 230 comprises an outside surfaceof type six or eight faces engaged in the surfaces complementary to thebody 210 to immobilize the second sleeve in rotation in the body. Otheranti-rotation devices enabling translation are possible, like retainerdevices, keys or other splices.

The first portion 232 of the second sleeve covers a second portion 228of the first sleeve 220, adjacent to the second end of the first sleeve.A surface external to the second portion 228 of the first sleeve formsan external shoulder and an internal surface of the first portion 232 ofthe second sleeve forms a stop, close to the front end of said firstportion of the second sleeve, receiving the shoulder of the firstsleeve. The shoulder and the stop comprise the complementary bearingsurfaces enabling the transfer of a translation movement of the secondsleeve 230 to the first sleeve 220 toward the rear end 218 of the body.Other drive means can be used in translation of the first sleeve.

The body 210 also comprises a driving means able to drive the firstsleeve 220 in translation and in rotation, and able to drive the secondsleeve 230 in translation. The driving means comprise a shaft 240extending along the X axis between the second end of the first sleeve220 and the rear end 218 of the body. The shaft is rotatably mountedaround a longitudinal axis of said shaft and can be rotated in the twopossible rotation directions around its axis. In the front, the shaft isequipped at a first end with a first free wheel 242, positioned at aninterface with the second portion 228 of the first sleeve 220. The shaftcomprises at a second end near the rear end 218 of the body a drivingmeans for rotation (not shown) that can bring the shaft in a rotationdirection and in the reverse direction. A second free wheel 244 isarranged around the shaft 240, adjacent axially between the first freewheel 242 and the driving means for rotation of the shaft. A drivingelement 246 is arranged coaxially around the second free wheel 244.

Each free wheel 242, 244 conventionally comprises an internal ring andan external ring such that, in a rotation direction, the free wheelturns freely without securing the internal ring with the external ring—aphase called free wheel, and in the other rotation direction theinternal ring is secured to the external ring and transfers a torque tothe part linked to the external ring.

The first free wheel 242 is positioned to drive the first sleeve 220 inrotation during a rotation of the shaft in a first rotation direction.The second free wheel 244 is positioned to drive the driving element 246in rotation during a rotation of the shaft in a second rotationdirection, reverse to the first rotation direction. The free wheels 242and 244 are in free wheel phase in opposite directions of rotation. Thefirst free wheel 242 transfers a torque in the rotation directionidentical to the screwing direction of the pin 12 in the sleeve 14.

The first free wheel 242 is slidably mounted along the shaft 240 using athird ring 248 coaxial with the shaft that can slide on the shaft. Thethird ring 248 and the shaft 240 are secured in rotation, for example,via a hexagonal face or another anti-rotation form, or via any othermechanical means such as a retainer device or key. The third ring 248comprises a stop 250 in bearing, on the one hand, against an internalshoulder of the second portion 228 of the first sleeve, and on the otherhand, against the first free wheel 242. A third compression spring 252is housed around the shaft 240, between an internal shoulder of thedriving element 246 and the third ring 248.

The driving element 246 comprises a first portion 254 positionedcoaxially around the second free wheel 244, and a second portion 256extends coaxially around the shaft, at a distance from the shaft. Inthis example, the first portion 254 of the driving element comprises anexternal driving surface for rotation, for example, for example ahexagonal faces, and the second portion 256 of said driving elementcomprises an external surface of ball screw type. The ball screwscooperate with an internal surface of the second sleeve 230 of the ballscrew type. Due to the helical link between the driving element 246 andthe second sleeve 230, and the fact that the second sleeve 230 isimmovable in rotation in the body 210, the rotation of the drivingelement 246 brings the translation of the second sleeve 230 toward therear of the body when the shaft is subjected to a rotation in thedirection of transmission of the torque of the second free wheel. Inthis rotation direction, the first free wheel 242 is in free wheelcondition and does not bring the first sleeve into rotation.

Other types of helical links between the driving element and the secondsleeve are possible, such as links using traditional pins/nuts, rollerscrews or worm screws.

The first portion 254 of the driving element 246 forms a collar 258extending radially outwardly. A spiral spring 260 is housed in theradial direction in the body 210 around the first portion 254 of thedriving element, an end of said spring being secured to said firstportion 254, whereas the other end is secured to the body 210. Thespiral spring is contained in the axial direction between the collar 258of the first portion of the driving element and a stop 262 of the body.The spiral spring 260 is tightened on itself when the shaft is subjectto a rotation in the blocking rotation direction of the second freewheel 244. The spiral spring unwinds when the shaft is subject to arotation in the reverse rotation direction.

As a variant, the spiral spring can be replaced by a torsion spring. Thespiral spring is less cumbersome and provides more adjustment latitudethan the torsion spring.

The installation tool also comprises an ejector comprising a rod 272 ofwhich one end can slide in the shaft 240, a fourth compression spring274 housed in a space within the shaft 240 and pushing the rod 272. Theejector also comprises a bearing element 276 positioned at an endopposite the rod 272, which can slide in the first sleeve 220 and bearsagainst an external surface of the first portion 28 of the grippingelement 16 of the pin. In resting state, in which no fastener isinserted in the equipment nose, the bearing element 276 of the ejectoris pushed by the fourth compression spring 274 forward to face theopening 216 of the body 210.

The installation procedure for a blind fastener 10 using the equipmentnose 200 will now be described, in relation to the FIGS. 3 to 7.

In a first step, an operator grips a fastener 10 in a state representedin FIG. 1 and inserts it via the front opening 216 of the body. Thegripping portion 28 of the pin pushes the movable elements 224 radiallyoutwardly which click into place in the blockage portion 30 of thefastener once the first gripping portion 28 of the pin is completelyinserted in the equipment nose (FIG. 3). The movable elements 224 thuspresent an external diameter less than the internal diameter of thefirst ring 222, which is free to slide forward under the action of thefirst compression spring 226, so as to capture the movable elementsaround the gripping portion of the fastener (FIG. 3) and to block thefastener 10 in the equipment nose in the axial direction.

When the first portion 28 of the gripping element is entirely containedin the equipment nose 200, the bearing element 276 of the ejector,pushed rearward, compresses the fourth compression spring 274 in theshaft 240.

The fastener 10 is then inserted in at least two elements of structure400 to be assembled, presenting a front face 402, next to which thefastener is inserted, and a blind face 404 opposite to the front face.For simplicity, the structure is represented generally on FIGS. 3 to 6without representing the elements that are assembled to constitute it.The contact surface 214 of the body lies on the collar 40 of thefastener.

The first step consists of forming a bulb against the blind face 404 ofthe structure. To do this, the shaft 240 is rotated in the rotationdirection of the second free wheel 244. The spiral spring 260 istensioned, a translation is imposed on the second sleeve 230 via thepin/ball nut link. The second sleeve 230 moves rearward (FIG. 4—arrowF1) and drives the first sleeve 220 by engaging the bearing surfaces ofthe shoulder of the first sleeve 220 and the first stop of the secondsleeve 230, as well as the third ring 248 positioned around the shaft,thereby causing the first free wheel 242 rearward, and compressing thethird compression spring 252.

The first sleeve 220 and the first ring 222 drive the gripping element16 of the pin rearward, and thus the threaded portion 26 of the pin andthe tapping 48 of the sleeve toward the blind face 404 of the structure,until the formation of a bulb 58 of which a face comes in abutmentagainst the blind face 404. The head 20 of the pin 12 is thus containedin the body 210 of the installation tool. The contact surface 214 of thebody still holds the sleeve 14 in the structure 400 (FIG. 4).

The second step consists of screwing the pin 12 in the sleeve 14 tobring the head 20 of the pin in the collar 40 of the sleeve. Therotation exerted on the shaft 240 is stopped and a reverse rotationmovement is imposed. The combined actions of the spiral spring 260 andthe third compression spring 252 drives the second sleeve 230 intranslation and the third ring 248 forward (FIG. 5, arrow F2), whereasthe rotation of the shaft in the rotation direction of the first freewheel 242 brings the first sleeve 220 into rotation in the screwingdirection of the pin, in the forward direction. In this rotationdirection, the second free wheel 244 is in free wheel phase, and doesnot bring the driving element in rotation 246.

FIG. 5 illustrates the end of this movement: the first sleeve 220, thesecond sleeve 230, the first free wheel 242 and the third ring 248 arereturned to their initial position as seen in FIG. 2, the head 20 of thepin once again in abutment against the collar 40 of the sleeve.

The third step consists of finalizing the installation of the rivet byfracturing the gripping element 16 of the pin by continuing to turn theshaft 240 in the rotation direction of the first free wheel 242. Therupture groove 18 is designed to fracture beyond a certain tensiontorque ensuring the desired tightening for the fastener. It thereforefractures once the threshold is reached, leaving the head 20 flush withthe front surface 402 of the structure (FIG. 6).

To eject the broken gripping element 16, the operator grips the secondring 228 and pulls it rearward of the body. Using a retainer system, thefirst ring 222 is pulled rearward (FIG. 7). In doing so, the first ring222 frees the front end of the movable elements 224 which are once againradially movable. The ring 222 no longer maintaining the movableelements 224 in the blocking portion 30 of the gripping element 16, thebearing element 276 of the ejector is pushed forward under the action ofthe fourth compression spring 274, which ejects the gripping element 16from the equipment nose 200. The ejector also pushes the movableelements radially, which take their initial positions in FIG. 2, holdingthe first ring 222 in a rear position when the operator releases thesecond ring 228, and the second compression spring 229 returns thesecond ring 228 to the initial position of FIG. 2. Another blindfastener can be installed according to the same procedure.

This manual installation tool manual can be used with all fasteners of“pull-torqued” type by adapting the movable elements 224 and thegripping means of the sleeve 220 to the shape of the gripping element 16of the pin.

Of course, the installation tool 200 can also install fasteners withprotruding heads.

1. An installation tool for a fastener in a structure via a front faceof said structure, said fastener being of the type including a pincomprising a shank with a head and a threaded end, a gripping elementthat can be fractured with the application of a predetermined fracturetorque and a threaded sleeve capable of becoming deformed toward theoutside to form a bulb against a rear face of said structure: a body,substantially a revolution, extending along a longitudinal X axis,comprising a first end in front of an axial opening allowing feedthroughof the gripping element and the fastener head, a first sleeve movableaxially and rotationally in the body, capable of driving the grippingelement of the pin in axial translation and in rotation about the Xaxis; a second sleeve movable axially in the body and immovable inrotation, said second sleeve being arranged to drive the first sleeve inaxial translation; the means for rotation about the X axis comprising aturning shaft provided: with a first free wheel that can drive the firstsleeve in rotation in a first rotation direction of the shaft, with asecond free wheel that can rotate a driving element positioned coaxiallyaround said second free wheel in a second rotation direction of theshaft, opposite to the first rotation direction, with the drivingelement cooperating via helical link with the second sleeve so as tomove said second sleeve in axial translation.
 2. The installation toolfor a fastener as claimed in claim 1, in which the driving element is athreaded pin, a ball screw, a roller screw or a worm screw.
 3. Theinstallation tool for a fastener as claimed in claim 1, in which thefirst sleeve comprises movable elements capable of cooperating with theblocking portion of the gripping element of the fastener to secure saidfastener in the axial direction with said first sleeve.
 4. Theinstallation tool for a fastener as claimed in claim 3, comprising afirst ring positioned on the first sleeve capable of sliding between afirst position in which the movement of the movable elements is blockedin the radial direction and a second position in which the movement ofmovable elements is free in the radial direction.
 5. The installationtool for a fastener as claimed in claim 4, comprising a second ringcapable of sliding according to the axial direction on the body andinterfaced with the first ring to bring the first ring only to thesecond position.
 6. The installation tool for a fastener as claimed inclaim 1, in which the first free wheel is assembled sliding along theaxial direction on the shaft.
 7. The installation tool for a fastener asclaimed in claim 6, in which the first free wheel is assembled on athird ring assembled sliding along the axial direction on the shaft. 8.The installation tool for a fastener as claimed in claim 7, in which acompression spring is positioned between the third ring and the drivingelement.
 9. The installation tool for a fastener as claimed in claim 1,including a spring device attached to an end of the driving element andanother end to the body, this spring device is tensioned during rotationof the shaft in the second direction and slackens to push the drivingelement when the rotation of the turning shaft is stopped and/orreversed.
 10. The installation tool for a fastener as claimed in claim9, in which the spring device is a torsion spring or a spiral spring.11. Installation procedure for a fastener using an installation tool inaccordance with claim 1, such procedure comprising the following steps:engaging the gripping element of a fastener to be installed in theopening of the body of the installation tool to secure said fastener intranslation and rotation with the first sleeve and engaging the fastenerin a perforation in the structure, then; rotating the shaft in thesecond direction to move the second sleeve in axial translation, whichbrings the first sleeve in axial translation in the pulling direction ofthe fastener pin, for a distance ensuring the formation of a bulb viadeformation of the sleeve, then; rotating the shaft in the firstrotation direction to bring the pin in rotation up to the tighteningtorque of the pin for which the gripping element separates from the restof the pin via a fracture at the level of a shear groove.